RE: Odd M16 Bolt

[MistWolf]

The rings are definitely damaged, caused by lack of support in the cut-out areas

[JBowles]

I worked this up in Solidworks, a normal bolt partially covers the exhaust vents on the carrier in the unlocked position. The cuts on that bolt spot on to where they would need to be, for the exhaust ports to be unobstructed.

[sinister]

It's broke. If it is parkerized it was broke and they re-finished it.

It ain't for an M16, M16A1, M16A2, M16A3, M16A4, M4/M4A1, or M231.

Note the "Divots" coincide with the vent holes on the right side of the bolt carrier (in the depression to accommodate the ejection port cover plunger and spring).

Shit-can it, replace with a new one, continue with work.

[Ned Christiansen]

That rearmost ring would deform every time I'd think unless there was a gap locator in there. Which I would not think could be trusted.

How about this-- an experiment to get gas under the rings, pressuring them outward against the carrier bore, to effect a better seal? If so I'd say this is the kind of experiment that eventually gets "failed" added as a prefix.

[Iraqgunz]

I don't have the bolt. One of my associates did and he doesn't have access to it now.

Any updates?

[halfmoonclip]

Just an observation- the scallops & notch would make the rings easier to remove or install quickly. Slip an end under the tab and screw on. Not that it's needed, just conjecture as to why someone might intentionally scallop and leave the tab.

I'm trying to remember where, but I think I've seen a similar approach used to facilitate installation of split rings in a non-firearms application.

This suggestion makes as much sense as anything; replacing the rings can be a futzy job.
Moon

[sinlessorrow]

What is most interesting is that it appears to line up perfectly with the gas vents on the carrier.